Mitochondrial levels globally modulate gene expression

Gene expression activity is heterogeneous in a population of isogenic cells. Identifying the molecular basis of this variability will improve our understanding of phenomena like tumor resistance to drugs, virus infection or cell fate choice. The complexity of the molecular steps and machines involved in transcription and translation could introduce sources of randomness at many levels, but a common constraint to most of these processes is its energy dependence. In eukaryotic cells most of this energy is provided by mitochondria. A clonal population of cells may show a large variability in the number and functionality of mitochondria. Cell-to-cell differences in mitochondrial content, probably originated by asymmetric segregation at cell division, contribute to heterogeneity in gene products.